This invention relates to the field of folding, portable chairs or seats.
U.S. Pat. No. 774,873 to Fuchs discloses an X-frame camp seat, with a fore and aft, crotch support seating. Fuchs discloses what may be described as a bicycle seat or saddle, having a broad rear section and a narrow frontal section. Further, Fuchs' seat is large, (note FIGS. 4-6) suspended from the body by straps. Fuchs is notable for using a particular bottom mounted spring (item 7) to force the seat apart into a fixed seating position as the seat is lowered to the ground.
U.S. Pat. No. 2,201,630 to Murtha discloses a cross frame or x-frame chair (called a Stick Chair) with two seat straps. A modified form of the chair pivots the sticks on a sliding member within a channel so that when closed the chair may be contained within the channel, and when open the channel serves as a third tripod leg.
U.S. Pat. No. 3,544,051 to Norman, disclosing a portable cane seat and gun rest, discloses a single point seat support. The structure does not utilize tension on the seat member for support but rather has a cross brace member (114), forming a solid triangular brace upon which the "saddle" is mounted.
U.S. Pat. No. 4,029,278, discloses a form of hunting stool in which a leveling leg is used to support the stool on uneven ground. Again, this leg provides the typical tripod support.
U.S. Pat. No. 4,328,992 to Ohanian discloses an adjustable x-frame stool which differs in that it has a gear revolving roller upon which the flexible seat material is rolled, and which may be set to varying degrees of extension, varying the height of the seat This illustrates that X-frame seats are not fully conformable, as the positioning of the legs on the ground determines the spacing of the seat supports.
U.S. Pat. No. 4,544,203 is a kind used by sunbathers. This is an x-frame headrest symmetrical, in the sense that it has cloth members on both the upper and lower surfaces, as support to prevent the headrest from sinking into the sand or ground. This patent notes the question of supporting the footing members of the seat against penetration into the ground. Norman's cane patent discloses a plate to prevent penetration into relatively soft terrain (item 28). This plate is, however, mounted well above the described foot and apparently is some form of a backup rather than being a regular ground foot.